suspend fun <T> retrying

Retrying.kt

import kotlinx.coroutines.CancellationException
import kotlinx.coroutines.delay

suspend fun <T> retrying(
    timesMax: Int = 3,
    delayMillis: (Int) -> Long = { (it + 1) * 1000L },
    needRetry: (Int, Throwable) -> Boolean = { _, _ -> true },
    block: suspend () -> T,
    onResult: suspend (T) -> Unit,
    onFinalError: suspend (Throwable) -> Unit,
    finally: suspend () -> Unit = {},
) {
    try {
        if (timesMax <= 0) {
            onFinalError(IllegalArgumentException("timesMax: $timesMax"))
            return
        }
        for (triedTimes in 0..timesMax) {
            try {
                val result = block()
                onResult(result)
                return
            } catch (t: Throwable) {
                t.rethrowIfCancellation()
                if (triedTimes >= (timesMax - 1) || !needRetry(triedTimes, t)) {
                    onFinalError(t)
                    return
                }
                delay(delayMillis(triedTimes))
            }
        }
    } finally {
        finally()
    }
}

suspend fun <T> retrying(
    timesMax: Int = 3,
    delayMillis: (Int) -> Long = { (it + 1) * 1000L },
    needRetry: (Int, Throwable) -> Boolean = { _, _ -> true },
    block: suspend () -> T,
): T {
    if (timesMax <= 0) {
        throw IllegalArgumentException("timesMax: $timesMax")
    }
    for (triedTimes in 0..timesMax) {
        try {
            return block()
        } catch (t: Throwable) {
            t.rethrowIfCancellation()
            if (triedTimes >= (timesMax - 1) || !needRetry(triedTimes, t)) {
                throw t
            }
            delay(delayMillis(triedTimes))
        }
    }
    throw IllegalStateException("Retrying completed; Not expected to get here!")
}

/*
 * https://kotlinlang.org/docs/cancellation-and-timeouts.html#run-non-cancellable-block
 * https://stackoverflow.com/a/62221582/2276980
 */
fun Throwable.rethrowIfCancellation() {
    if (this is CancellationException) {
        throw this
    }
}

val loaded = retrying(
timesMax = 10,
delayMillis = { ((it + 1) * 1000L).coerceAtMost(10_000L) }
) {
Api.client.get(Url(url)).readBytes()
}